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Re-Engineering Water Storage in the Everglades: Risks and Opportunities
EVERGLADES AGRICULTURAL AREA
The Everglades Agricultural Area (EAA) immediately south of Lake Okeechobee is characterized by rich peat soils (histosols). The area is devoted primarily to the production of sugarcane with small acreages devoted to vegetables, rice, beef cattle, and sodgrass. The annual value of production in this area in the early 1990s totaled $640 million (Alvarez et al., 1994). It is known that the peat soils oxidize on contact with the atmosphere, and this oxidation has caused the land surface to subside as progressive increments of the peat itself were lost though the twentieth century. The ultimate demise of Everglades agriculture was first predicted over 50 years ago, but there has been a long controversy over the rates of oxidation and the exact time when there would be insufficient soil over the bedrock to permit agriculture to be practiced (Douglas, 1947; Stephens and Johnson, 1951). Moreover, some have argued that agriculture could be practiced on the remaining mineral soils on a long-term sustainable basis. Indeed, economic rather than strictly agronomic factors may affect the near-term fate (next 5-20 years) of agriculture production in the EAA. Much of the EAA is devoted to sugarcane production, which effectively is subsidized by import duties on foreign-grown sugar and shielded from Cuban sugar production by import restrictions that have been in place since the 1960s (e.g., Mayer, 2001). Those restrictions may well change if there are changes in the government of Cuba, its policies, or those of the U.S. government.
Another economic stimulus for removing EAA land from agricultural production is the continuing strong migration of people to south Florida, which shows no sign of abating. At some point in the perhaps not too distant future, agricultural interests may decide that some of their land is more valuable for development into retirement communities, golf courses, and related land uses than for agricultural production. If this were to happen, it would create additional problems for the Everglades restoration because it would impose continued demands for reliable water supplies and at the same time decrease the amount of land that could be used for water storage and also possibly make it more difficult to use adjoining lands for storage.
Aside from its potential use for construction of surface reservoirs, an EAA that no longer was used (in whole or part) for agricultural production also could be flooded and allowed to revert to its natural wetland condition. It would take many centuries for the wetland to accrete the amount of peat soil present before drainage and agriculture production began, but a semblance of a natural marsh system probably could be established rather quickly. This system would tend to act as a giant stormwater treatment area, removing nutrients as the water slowly moved south. As Odum and Odum (2003) pointed out, such an approach could reestablish the original pattern of “longitudinal succession” within the Lake Okeechobee-Everglades system–that is, nutrient-rich water from the lake would pass through a eutrophic slough south of the lake and lose nutrients by plant growth and peat accretion before entering the oligotrophic Everglades to the south.
CAN LAKE OKEECHOBEE PROVIDE MORE WATER STORAGE?
Often called the liquid heart of the Everglades, Lake Okeechobee is near the geographic center of the series of ecosystems constituting the Greater Everglades. Given the attention it has received and its actual and potential importance in the Everglades restoration, it is treated in some detail here.
In terms of surface area, Lake Okeechobee is the second largest freshwater body located wholly within the United States (Lake Michigan is the largest), but its volume is very small